This invention relates to electrical insulators for electric fence wires and which are commonly mounted on vertical metal fence posts, for example, of the general type disclosed in U.S. Pat. Nos. 4,049,905, 4,077,611, 4,845,317 and 6,353,187, the disclosures of which are herein incorporated by reference. As disclosed in these patents, the insulator is commonly molded of an insulating plastics material and is adapted to be attached to a conventional T-type metal fence post at a selected vertical height or elevation according to the desired position of the electric fence wire. It is also common to mount two or more of the insulators on each fence post when it is desired to have vertically spaced electric fence wires.
In any such insulator, it is desirable for the insulator to mount quickly and positively on the fence post so that the insulator cannot be pulled off or slide or shift vertically on the post after it has been installed. It has also been found desirable to avoid relying on the flexibility of the molded plastics material in the portion of the insulator which mounts on or grips the metal fence post. If the spring property of the plastics material relaxes, the insulator may pop off or slide down the post, thereby allowing electric fence wire to sag and/or short out by contacting the fence post. It is also sometimes desirable to space the electric fence wire from the post to avoid grounding of the wire and to facilitate mowing of weeds directly under the wire so as to prevent an electrical short by the weeds.